Revert "Adjust to changes in Gerrit core" Revert submission 283559-currentuser-remove-cache-key Reason for revert: Causes a latency regression for some hosts Reverted Changes: I76bfd3ebc:Adjust to changes in Gerrit core If7ccfd9a4:Remove unused CurrentUser#cacheKey method I1378ad083:Remove PerThreadCache Change-Id: I2bfe41d8acc4b325bb59b3ae099661300d84454e